Effects of acute stress on the day of proestrus on sexual behavior and ovulation in female rats: participation of the angiotensinergic system.
ABSTRACT Physical or emotional stress can affect the female reproductive physiology and angiotensin II (Ang II) is a hormone that participates in the stress response and also in the control of reproductive hormones. The present study aimed at evaluating the effects of acute stress in the morning and afternoon of proestrus on sexual behavior and ovulation and the participation of Ang II in the stress-induced effects. Female rats with regular estrous cycles were used. Several different stress protocols were tested in the morning and in the afternoon of proestrus: restraint stress 10 min; restraint stress 1 h and ether stress, respectively. The participation of Ang II was evaluated by injecting Ang II receptor antagonists (losartan and PD123319) 15 min before stress. The lordosis quotient was recorded and the number of oocytes was counted. Plasma levels of luteinizing hormone, progesterone, prolactin and corticosterone were measured. All types of stress in the morning of proestrus induced a reduction in the number of oocytes. Restraint stress (1 h) in the afternoon of proestrus induced a significant reduction in the lordosis quotient. Peripheral and central losartan, but not PD123319, injections partly reverted the effects of stress on ovulation in the morning of proestrus. Acute stress in the morning of proestrus also reduced luteinizing hormone, progesterone and prolactin surges later on the same day. In conclusion, acute stress on the day of proestrus can affect female reproductive physiology. Moreover, the angiotensinergic system, through AT(1) receptors, participates in the effects of acute stress in the morning of proestrus.
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ABSTRACT: Of the numerous neuropeptides identified in the central nervous system, only a few are involved in the control of sexual behavior. Among these, the most studied are oxytocin, adrenocorticotropin, α-melanocyte stimulating hormone and opioid peptides. While opioid peptides inhibit sexual performance, the others facilitate sexual behavior in most of the species studied so far (rats, mice, monkeys and humans). However, evidence for a sexual role of gonadotropin-releasing hormone, corticotropin releasing factor, neuropeptide Y, galanin and galanin-like peptide, cholecystokinin, substance P, vasoactive intestinal peptide, vasopressin, angiotensin II, hypocretins/orexins and VGF-derived peptides are also available. Corticotropin releasing factor, neuropeptide Y, cholecystokinin, vasopressin and angiotensin II inhibit, while substance P, vasoactive intestinal peptide, hypocretins/orexins and some VGF-derived peptide facilitate sexual behavior. Neuropeptides influence sexual behavior by acting mainly in the hypothalamic nuclei (i.e., lateral hypothalamus, paraventricular nucleus, ventromedial nucleus, arcuate nucleus), in the medial preoptic area and in the spinal cord. However, it is often unclear whether neuropeptides influence the anticipatory phase (sexual arousal and/or motivation) or the consummatory phase (performance) of sexual behavior, except in a few cases (e.g., opioid peptides and oxytocin). Unfortunately, scarce information has been added in the last 15 years on the neural mechanisms by which neuropeptides influence sexual behavior, most studied neuropeptides apart. This may be due to a decreased interest of researchers on neuropeptides and sexual behavior or on sexual behavior in general. Such a decrease may be related to the discovery of orally effective, locally acting type V phosphodiesterase inhibitors for the therapy of erectile dysfunction.Progress in Neurobiology 07/2013; · 10.30 Impact Factor
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ABSTRACT: Catecholamines play an important role in embryogenesis, and data obtained in the rodent model indicate that they can act even during the preimplantation period of development. Using RT-PCR with specific oligonucleotide primers distinguishing among all members of the adrenergic receptor family, we examined expression of adrenergic receptors in bovine and rabbit oocytes, morulas and blastocysts. We found several profiles of adrenoceptor mRNA expression. Transcripts for some receptor subtypes (bovine alpha 2 receptors, rabbit α2A, α2C, β1 and β2 receptors) were detected at all examined stages, which suggests receptor expression throughout (or at most stages) the preimplantation developmental period. Expression in oocytes but not at later stages was found in only one adrenoceptor subtype (rabbit α1B). In contrast, mRNA for several adrenoceptors was found in embryos but not in oocytes (bovine beta adrenoceptors and rabbit α1A). Nucleotide sequences of our PCR products amplified in rabbit oocytes, and preimplantation embryos represent the first published mRNA sequences (partial sequences coding at least one transmembrane region) of rabbit α2C, β1 and β2 adrenoceptors. Our results suggest that the expression of adrenergic receptors can be a general feature of mammalian oocytes and preimplantation embryos. On the other hand, comparison of three mammalian species (cattle, rabbit and mouse) revealed possible interspecies differences in the expression of particular adrenoceptor subtypes. Our results support the opinion that stress mediators can act directly in cells of preimplantation embryos.Reproduction in Domestic Animals 08/2013; · 1.18 Impact Factor
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ABSTRACT: Adsorption of water to fractal dust grains during accretion has been proposed as a possible source of water for rocky planets. We have used computer simulations to study the feasibility of chemisorption onto forsterite dust grains by investigating the adsorption of dissociated water to stoichiometric and defective surfaces. Defects were modeled using steps, corner sites and vacancies on different forsterite surfaces. Our results show that water dissociation is expected on the stoichiometric (100) surface but not on the stoichiometric (010) surface. However, the energies released by dissociative adsorption at steps and corners indicate that the energetic barrier to chemisorption on the (010) surface would be favorable if these features were present. Steps and corners on all surfaces studied produced Mg sites that have low coordination and thus were highly reactive, favoring the dissociation of water. Terrace size between the steps was shown to have a limited effect on the final energies, although smaller terraces created more reactive Mg sites at corners. A simple Langmuir model was used with the energetic data from our simulations to examine the effectiveness of water adsorption at temperature and pressure conditions applicable to the accretion disk. The findings of this study suggest that water would be strongly chemisorbed at fractal forsterite surfaces even at low partial pressures suggesting that water could be retained during planetary accretion.Earth and Planetary Science Letters 11/2010; 300. · 4.72 Impact Factor